Sighted people are able to update their knowledge of their relative position while they act in an environment even when there is no continuous visual information available. For example, people usually have few problems finding their way through their house after they have switched off light. Similarly, people typically do not lose orientation relative to parts of the environment when they go out of sight (e.g. parts that moved behind the person while walking). The goal of the proposed studies is to elucidate the cognitive processes that underlie this fundamental capability of spatial updating without vision. At the same time, understanding non-visual spatial updating will help us to understand more complex skills that are based on this fundamental capability, such as navigation and orientation in space. It is well known that many people get easily lost or have difficulties maintaining orientation. Understanding what it takes to keep track of environmental changes and to stay oriented will enable us to formulate strategies that can be used to train navigation and orientation in space. Although it is clear that acting in the environment is a key element, there are no systematic investigations that examine what aspects of action are crucial for non-visual spatial updating to occur. Much previous research has been based on a path-integration (bottom-up) hypothesis, assuming that spatial representations are mentally updated by means of movement-produced cues (e.g. proprioceptive information during locomotion). However, the existing evidence is also consistent with the (top-down) hypothesis that action plans or intentions, specifically, the anticipated changes in the environment produced by movements, determine spatial updating performance. Four experiments will determine the degree to which sensory-based, bottom-up and cognitive, top-down processes govern spatial updating by testing these variables against each other.